Identification of Pathogens and Evaluation of Resistance and Genetic Diversity of Maize Inbred Lines to Stalk Rot in Heilongjiang Province, China

Maize stalk rot, caused by multiple pathogens, is a serious soilborne disease worldwide. Composition of pathogens causing maize stalk rot and resistance of maize inbred lines in Heilongjiang Province, China, are not well understood. In this study, 138 fungal isolates were collected from different maize-producing areas in Heilongjiang Province, which were identified as Fusarium graminearum (23.2%), F. subglutinans (18.9%), F. cerealis (18.9%), Bipolaris zeicola (13.0%), F. brachygibbosum (13.0%), F. temperatum (7.2%), and F. proliferatum (5.8%). Among them, F. graminearum (>20%) was the predominant species among the isolates causing maize stalk rot. B. zeicola had not previously been reported causing maize stalk rot in China. Resistance of 67 maize inbred lines to maize stalk rot was assessed, and 24 lines (35.8% of them) were highly resistant or resistant, indicating that approximately 65% of these lines were susceptible to maize stalk rot. Maize inbred lines were analyzed using simple sequence repeat markers and divided into five genetic groups with 12 pairs of primers. Additionally, analysis of molecular variance indicated that 44.2% of the genetic variation in disease resistance was distributed among populations. This study provides insight into the genetic diversity of inbred maize and may contribute useful information for breeding stalk rot disease-resistant hybrids, and facilitates development of effective strategies for managing this destructive disease complex.